Field of the Invention
The present invention relates to a controller for a common-rail injection system which includes a plurality of fuel injectors, a common fuel supply line for the fuel injectors, a high-pressure pump for supplying the common fuel supply line with fuel, and a pressure sensor for determining the pressure in the common fuel supply line. In particular, this invention concerns a controller of a common-rail injection system of a diesel engine.
In the actuation of an engine, the precise dosage of the injected fuel quantity plays an essential role with regard to the subsequent combustion and the exhaust gases generated thereby. Due to production-related component variances of the fuel injectors and aging phenomena during the engine operation, the same must therefore be calibrated while the engine is running. This means that deviations or drifts in the actually injected fuel quantity must be detected, quantified and compensated by a corresponding adaptation of the injector actuation.
Description of Related Art
In this respect it is known for example from the German document DE19726100A1, European publication EP894965A1, and German document DE69112355T2 to calculate target injection quantities with reference to the engine operating condition and to perform the actuation of the fuel injectors on the basis of these target injection quantities. During the engine operation, the pressure drop caused by the injections in the common fuel supply line of the common-rail injection system is evaluated and the fuel quantity actually injected during the injections is determined therefrom. There is formed the difference of the pressure before the injection performed with a target injection quantity and after the injection, and thus the pressure drop caused by the injection is determined, by means of which in turn the actually injected fuel quantity is determined. By means of the results for preceding fuel injections, the actuation of the fuel injectors is adapted for succeeding fuel injections.